The present invention relates generally to electronic timepieces of the analog type.
In the prior art, a commonly used display mechanism for an analog display type quartz timepiece is arranged as shown in FIG. 1. The output of a stopping motor comprised of a stator 1, a coil 7 and a rotor 6 is transmitted to a wheel train having wheels 2,3,4, and 5, the output from the wheel train is transmitted to the display mechanisms, such as a second hand, a minute hand and an hour hand, or a calendar device under certain circumstances, through wheel trains (not shown) to drive the display mechanisms.
In FIG. 2, an example of the circuit construction for a conventional electronic timepiece is shown. The frequency of an oscillating signal from an oscillating circuit 10 is divided continuously by a frequency dividing circuit 11. These frequency divided signals are converted into two signals each having a pulse width of 7.8[ms] and a period of 2[sec] are being dephased by 1[sec] from each other by using a pulse combining circuit 12, and these signals are applied to the inputs 15 and 16 of driving inverters 13a and 13b. Therefore, a reversing driving pulse which changes the direction of the current every one second is applied to the coil 7 and, the rotor 6 magnetized so as to have two poles can be sequentially rotated by steps of 180 degrees. An example of the driving current waveform of the coil is shown in FIG. 3.
The pulse width of the driving pulse (such as 7.8[ms] in the foregoing example), the resistance value of the coil, the number of turns in the coil, the sizes of the parts of the stepping motor and other porometers are designed so as to drive the stepping motor in a stable manner even though the electronic timepiece may be subjected to adverse conditions, such as, the load of the wheel train becomes large due to the addition of calendar function, the timepiece is placed in a magnetic field, or the internal resistance of a battery increases due to low temperature. Therefore, the timepiece dissipates much power so as to assure stable operation under the above-mentioned adverse conditions although the timepiece does not require such a large torque while operating under normal conditions. This fact prevents reduction of the total power consumption in the electronic timepiece.